This application building on a randomized clinical trial carried out in primary care to study trajectories of depressive symptoms and medical comorbidity in relation to the outcomes of Major Depression and suicidal ideation at 2 years aligns with the NIMH Strategic Plan and is submitted in response to PA-07-082, "Risk factors for psychopathology using existing data sets," released 11 May 2007. Recent studies have demonstrated that a variety of primary care interventions can improve late life Major Depression outcomes. However, these interventions have not been found to be effective for minor depression. While some research has previously identified subtypes of depression, little work has focused on subtypes of late life depression, and that work has been conducted in cross-sectional data and not in the context of an intervention trial. The specific aims of this study are: (1) To identify subgroups of primary care elderly patients based on baseline characteristics and two different types of longitudinal profiles: 1) depressive symptoms and 2) overall medical comorbidity, and the association of subgroups with criterion-based Major Depression and/or suicidal ideation at 2 years;(2) To assess whether the different subgroups identified in Aim 1 on the basis of either depressive symptoms or overall medical comorbidity modify the effect of the collaborative care intervention on criterion- based Major Depression and/or suicidal ideation at 2 years, such that the intervention will show significant effects in certain subgroups;and (3) To assess how the effect modification of the intervention effect on criterion-based Major Depression or suicidal ideation at 2 years in Aim 1 is mediated by varying intensity of exposure to antidepressant medication or psychotherapy. To accomplish these aims, we will capitalize on screening, clinical assessment, treatment, and follow-up assessments which have occurred for up to 2 years in PROSPECT (the "Prevention of Suicide in Primary Care Elderly: Collaborative Trial"). In all, 1,226 patients, including all patients who screened positive for depression and a random sample of patients who screened negative, were enrolled in the 2-year longitudinal study. The primary care practices were randomized into: (1) treatment as usual by the primary care practice (n = 617 patients);and (2) a guideline management intervention consisting of antidepressant or psychotherapeutic treatment for depression following AHCPR guidelines, revised for the elderly, under the responsibility of the primary care physician who is assisted by a Masters-level specialist (the intervention condition;n = 609 patients). Among the sample of 1226 primary care elderly patients, we want to emphasize that our analysis will be based on course of depressive symptoms and not DSM-IV diagnoses. We propose to supplement PROSPECT data with medication records to classify and quantify medical comorbidity over the course of the 2-year follow-up interval. The foundation for the analysis to improve our understanding of the dynamic association of course of depressive symptoms and medical comorbidity will be the general growth curve mixture model (GGCMM). This project can have a significant public health impact because a further understanding of the association of the course of depressive symptoms and the onset and course of medical comorbidity among elderly primary care patients would be a key step in intervening to improve recognition and treatment of late life depression. PUBLIC HEALTH RELEVANCE: The overall goal of this application is to identify subgroups of primary care elderly patients, based on baseline characteristics and two different types of longitudinal profiles: 1) depressive symptoms and 2) overall medical comorbidity, for whom the collaborative care intervention reduces the persistence or onset of Major Depression and/or suicidal ideation. This project can have a significant public health impact because a further understanding of the association of the course of depressive symptoms and the onset and course of medical comorbidity among primary care elderly patients would be a key step in intervening to improve recognition and treatment of depression in late life.